This is a resubmission of the Jerusalem Perinatal Cohort Schizophrenia Study. We plan to investigate the relations between prenatal exposures, obstetric complications, neonatal health, heredity and schizophrenia. The design has been improved over the prior submission by now including face-to-face interviews on 25 percent of cases, by including methods to address genetic influences and gene-environment interactions, and by clarifying the sizes of subgroups with overlapping prenatal, obstetric and neonatal data. The study is based on 92,500 pregnancies in Jerusalem from 1966-74 on whom a wealth of prospective data was collected from early in gestation for the Jerusalem Perinatal Study. The cohorts are now at the age of risk for schizophrenia. The incidence of schizophrenia will be identified by cross-linking the cohort data to the Israeli Psychiatric Case Registry. About 800 cases with schizophrenia are anticipated. The strengths of the study include its extensive data sets on demographics, prenatal exposures, obstetric complications, and infant condition at birth, health data through childhood, and data on parental health, including reported mental illness and consanguinity. It has sufficient power to examine even rare exposures. The aims are to examine whether prenatal exposures (including infections, nutrition, hormones, maternal stress, smoking, anemia, vaginal bleeding, x-ray's, Rh incompatibility) and obstetric complications are associated with an increased incidence of schizophrenia. The approach is illustrated with plausible risk factors. Furthermore, we have data on possible confounding, mediating variables and effect modification. We will propose causal pathways that may underlie the observed associations. We will conduct twin and sibling studies to examine hereditary factors and models for gene environment interaction. We will lay the groundwork to add military induction neuropsychological data on these subjects and establish the feasibility of future brain imaging studies.